The inhibition of CTSs has been widely explored over the last decades in the field of chronic inflammatory diseases [27,37,204,205], cardiovascular diseases [10,19,181], osteoporosis [70,71,72,73], arthritis [28,206], kidney diseases [30,31,32,84], pancreatitis [207], obesity [208,209,210], cancer [25,34,48,74,82,211], neurodegenerative diseases [39,41,184,185,212,213], and many other pathological states. This evidence concerns the gene CTSS and neurodegenerative disease.